Automatic starter



April 17, 1934.

S. RUBEN AUTOMATIC STARTER Filed Feb. 11, 1930 INVENTOR ATTORNEY Patented Apr. 17. 1934 UNITED]- STATES PATENT OFFICE AUTOMATIC STARTER Samuel Ruben, New Rochelle, N. Y assigns: to Van Manufacturing cemmlenfwllmluun, M, a corporation of Delaware Application February 11, 1930, Serial No. aw

1. Claims. ((71. 2.1-)

This invention relates to a device for use in starting apparatus requiring the introduction of resistance when connected to a lineso as to prevent excess current flow. Speciflcallyjit relates to a device for automatically controlling the current flow without manual operation of a control device such as the commonly used starting box or rheostat.

This device utilizes the electrical resistance properties of silver sulphide (or other compounds of the oxygen series of the sixth periodic group) when that material is produced in a certain manner and used in an inert atmosphere.

1 have found that if silver metal be heated un-' tflfl Resistance (ohms) s sm g a From the foregoing observed data, it is noted that the resistance drop with temperature is very large and it is also subject to other variables such as the voltage applied to the element in measuring the resistance. V

I have found that if the resistance element be operated under pressure in an inert gas such as helium that a device utilizing this 'efiect can be made that will maintain its characteristics.

If operated in air, oxidation of the sulphur takes place which by substitution produces metallic silver and sulphur dioxide which permanently alters the resistance of the sulphide element.

In a device for use in starting motors which application has been commercially found to be of advantage, the silver sulphide element is connected in series with thearmature and is heated by a refractory heater element such as a coiled tungsten filament which alsois heated by being connected in series with the load. The variable resistance element is preferably short circuited 6 after the motor is at operating speed and it is maintained in a shunt connection as long as the load is on. This allows it to cool so as to be at a high resistance when starting is again desired.

The heater element is also automatically disconnected when the starting has been accomplished.

The short circuiting is preferably accomplished by use of an independently heated thermostatic element. I

In order to more completely describe this invention, reference is made to the accompanying drawing in which is shown a glass bulb (1) which after having the parts therein assembled, has

been completely exhausted and filled under pressure with helium. The silver sulphide element (3) requires ageing which is accomplished by heating in an inert atmosphere to a temperature in excess of that to be used in practice or operation of the device. Nickel rings (4) and (2) positioned respectively at the top and bottom of the silver sulphide element (3) are adapted to establish the electrical circuit through the sulphide element and related connection. The

nickel rings, as are all supporting parts; are electrically welded to the support wires in the glass press or stem in a manner common to the lamp and vacuum tube art. Tungsten spring (5) is i used to take up the expansion of the heater filament (7) which is coiled and made of tungsten.

Supporting and welded to this filament is straight support wire (6). The thermostatic or bimetal strip (8) is made by rolling and brazing a brass sheet on an invar steel base and when heated bends toward the contact on ring (2). Around the thermostatic element (8) is wound insulated resistance wire (9) so that when the current becomes high enough, it heats the thermostatic strip causing it to move toward the sulphide tube,

short circuiting it and opening the heater con- 10o tact. As long as the load current flows, it keeps the heater circuit open and the sulphide resistance short circuited. Tungsten contact (10) is mounted on upper ring (2). The contacts (11) a mounted on thermostatic element (8) are ini- 5 In operation, when the switch (8) completes the circuit, the supply current flows through the tungsten coil heater circuit, which due to radiation and excellent thermal conductivity oi'the helium, rapidly heats the silver sulphide tube. This sulphide tube is in shunt with the heater. When the sulphide tube becomes heated, its resistance drops from an open circuit value to a very low resistance and when the current in the resistance (9) is great enough it heats the thermostat element (8) which bends over toward the sulphide tube, breaking the heater circuit between contacts (11) and (12) and short circuits the silver sulphide resistor element bymaking contact with contact (10) on upper ring (2). This allows the silversulphide to cool and return to its normal high resistance. The heat from the element (9) is insufiicient to adequately raise the temmrature of the silver sulphide to an ei iective value.

The tube can be mounted as shown in a molded base (15) with prong connections (13) and (14).

While silver sulphide is deemed preferable, I have also been able to accomplish the operating characteristics-described, though with less efiiciency, with other compounds of the oxygen series oi the sixth periodic group, such as cuprous oxide, antimony sulphide, cupric oxide and mix tures of oupric and antimony sulphide.

A thermostatic means for short circuiting the silver sulphide is considered preferable, but it is obvious that other means, such as electromagnetic means couldyalso be used in'a similar maner. It is also obvious that the shunting means could be external-ii desired.

What is claimed is:

1. In a sealed atmosphere of helium, the combination of a silver sulphide tube, a refractory heater coil with which it is in shunt, and a bimetailic thermostat element adapted to short circuit said silver sulphide tube at a predetermined temperature.

2. In combination, a sealed envelope having an atmosphere of helium and containing a V8.-='

riable resistance device employing as its variable resistance element a crystalline sulphur compound, associated thermal means within said envelope to effect the desired variations in resistance, and means to short circuit said variable resistance element when a predetermined resistance value is obtained. 1

3'. In ment consistingoia crystalline compound hav ing an abnormal negative temperature cceficient, associated thermal means to edeot the desired resistance variation, with means to $1 multaneously short circuit said vble resistance element and disconnect the thermal means.

combination, a variable resistance eleassassin 4. In a sealed envelope having an atmosphere having a heat conductivity greater than air, the combinatipn of a variable resistance element consisting of a crystalline compound having an ab normal negative temperature ccefiicient, associated thermal means within said envelope to effeet the desired resistance variation, with means to short circuit said variable resistance element and disconnect the thermal means.

5. In combination in a sealed envelope containing helium, a variable resistance element consisting of silver sulphide, associated thermal means within said envelope to efiect the desired resistance variation, with means to short circuit said variable resistance element and disconnect the thermal means.

6. A resistance device comprising the combina tion of a tube of a material having a negative temperature coefficient, a heater element miaiiy suspended within said tube, with means of simultaneously short circuiting said tube and disconnecting said axially arranged heater element.

7. A resistance device comprising the combination at a tube oi silver sulphide, a heater element axially suspended within said tube, with means of simultaneously short circuiting said tube and disconnecting said axially arranged heater clement.

e 8. A resistance device comprising the combination of a tube or" a material having a negative temperature coeiilcienta heater element axially suspended within said tube, with means of simultaneously short circuiting said tube and disconnecting said heater element, said combination arranged in an envelope containing an inert gas of high thermal conductivity.

,9. A resistance device employing a resistance element having a negative temperature ooenicient of resistance, temperature responsive means positioned in close proximityto said element to short circuit said element when a predetermined resistance value is reached, and means to maintain the temperature of said temperature responsive means when said resistance element is short circuited.

10. A resistance device employing a resistance element having a negative temperature coefii= cient oi resistance, temperature responsive means positioned in close proximity to said element to short circuit said element when a pre- 

